March 26, 2023


Delighting home maniacs

How Dangerous Are Ice Dams & Icicles for My Roof?

How Dangerous Are Ice Dams & Icicles for My Roof?

Ice dams and icicle hanging from a roof in the winter.

As the temperatures plunge and winter weather moves in, it’s not unusual to see ice forming on the edges of your roof, gutters, and eaves. And while ice can form for a number of reasons, it’s important to identify what’s causing the issue for your home—because a buildup of ice can result in costly roof damage and leaks. 

Let’s look more closely at what makes ice build up on your roof and why that’s a concern for your home.

What Are Ice Dams, and Why Do They Form? 

During winter, frozen precipitation tends to accumulate on your roofing. That snow and sleet should melt slowly and evenly, and then drain safely away through your gutter system. Properly insulated and maintained roofing usually does well at this.

The problem occurs when your roof is warmer in some spots and colder in others. The inconsistent temperature causes snow and sleet to melt quickly in warm spots, such as the top of your roof. But the moisture then gathers at the eaves—the edges of your roof. Your eaves are typically colder than the rest of the roof. If the temperature difference is too great, the moisture refreezes before it can drain through your gutter system. Ice builds up into a formation known as an ice dam.

The most frequent reasons for ice dams forming on your roof are:

Insufficient insulation in the attic

Insulation keeps heated air inside your home. Not only does this keep your interior comfortable and save you energy—but it also ensures snow and ice melt slowly, so your gutters can handle the runoff. If you don’t have enough insulation, wintry precipitation melts, runs down to your eaves, and freezes there, causing ice dams.

Faulty ventilation systems

Chimneys, dryer vents, and plumbing stacks are located on your roof, and they generate heat that can melt snow and sleet. These vents and outlets should be properly placed on the roof, not the soffit. Flashing, caulking, protective seals, and insulation should also be used to ensure that heat sources like these don’t lead to ice dams.

Weakened roofing

If your roof is worn down due to age and/or damage from issues like hail, it puts your home at risk. Worn, old roofing is less resilient to weather. It’s more likely to allow heat to escape in winter. Ice dams may be a sign that your roof has reached the end of its lifespan and needs replacement.

Damaged gutters

A related issue to worn roofing is broken gutters. They tend to go hand in hand because your drainage system is key to protecting your roof. If gutters can’t handle the drain-off of melting snow, ice will form in them during cold weather. That ice builds up into ice dams.

The Serious Problems that Ice Dams Can Cause 

While ice dams may look pretty at first glance, they can result in a lot of costly damage to your home if the underlying issue isn’t fixed. Because ice dams literally “dam” up moisture and prevent it from leaving the roof, you can suffer a lot of moisture-related hassles as a result.

Costly leaks 

With ice dams, moisture remains on your roof instead of draining—and the chances of a serious leak increase. You might see leaking in your attic, through the ceiling, and even underneath your siding—resulting in pricey repairs needing to be made.

Roofing shingle damage 

Since ice dams block gutters, the moisture can sneak under your roof shingles, weakening them. Roofing can loosen or break away, exposing your home to further moisture problems.

Broken gutter systems 

Ice dams block your drainage system, and as the ice melts and refreezes, gutters may crack or pull loose. This means water doesn’t drain safely away from your home. Instead, it penetrates your roof, gets under your siding, or seeps into your foundation—all costly issues that can ruin your home’s structure.

Wood rot 

The moisture from ice dams can reach your roof underlayment—the vulnerable wood structure that holds up your roofing. Rot can eat away at the wood, impacting your roof’s overall structure. Mold and mildew can form, leading to poor air quality, worsening allergies, and damaged personal property.

Worn-out siding 

Ice dams tend to melt down your siding instead of through your gutters. The exposure to that excess moisture can cause siding problems such as peeling paint, rust, rot, mold, or mildew.


Large chunks of ice from ice dams and icicles can potentially break and fall as temperatures change, leading to injuries to people and damage to personal property.

Do Icicles Mean You Have Ice Dams? 

It depends. If the icicles are few, small, and hanging only from your roof’s edge without noticeable ice buildup, that’s not usually a cause for concern

But if you’re seeing a lot of icicles, especially large ones, then you should consider them a sign your roof needs attention. If icicles form on siding or underneath roof overhangs, that means you have the same conditions that cause ice dams—so you should have your roof inspected.

Prevent Ice Dams with a Strong, Well-Insulated Roof   

If you’re noticing ice dams forming on your roof, that’s a sign that it may be time to get a new roof that provides reliable insulation and ventilation. At John McCarter Construction, our local roofing crew will happily come out, inspect your roof, and answer any questions you have.

Learn more about our roof replacement services—and get peace of mind your Michigan home is protected from damaging ice dams.